Stopping starlight may bring other Earths into focus

SUN FLOWER A starshade accompanying a proposed planet-hunting telescope, shown in an illustration, would block starlight and make it easier for the telescope to glimpse any planets orbiting distant stars.

BOSTON — When Voyager 1 pivoted back toward Earth from beyond Neptune in 1990, it snapped one of the most famous space pictures: the pale blue dot, with Earth appearing as a lonely speck of light. Astronomers are now designing a new generation of telescopes with hopes of taking a photo of another pale blue dot, this one orbiting a distant star. The proposals offer two contrasting ways of blocking out a distant star’s light, one with a giant shade traveling through space near the telescope and the other with shape-changing mirrors within the telescope.

NASA’s crippled Kepler space telescope has already shown that small rocky planets are common (SN: 4/5/14, p. 15). But Kepler’s data can’t distinguish Earthlike planets from dead ones more like Venus, Mars or something unimagined. On

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